The present invention relates to oxide and silicate based solids modified on the surface with bifunctional organosilicon compounds containing sulphur. In another aspect, the present invention relates to a process for producing modified inorganic support materials and to the use thereof as catalysts.
Treating such inorganic solids with organosilicon compounds is well known in the prior art. For example, polysulphanes (U.S. Pat. No. 4,514,231, German patent 33 14 742) or polyether-substituted silicon compounds (U.S. Pat. No. 4,151,154) are known for this purpose.
The problem underlying these patents, however, resided in determining how to improve the incorporability of inorganic fillers into rubber compounds and which rubber properties would simultaneously change advantageously as a result of such incorporation.
Sulphonic acid organic ion exchangers are known from the prior art which are modified with compounds containing sulphur, in particular containing mercapto groups, in order to increase the activity and selectivity thereof as condensation catalyst (EP A 0 630 878). However, a risk arises in the case of a compound containing sulphur becoming detached from the surface, thereby degrading the characteristics of the corresponding catalyst (EP A 0 583 712). Another disadvantage of this type of catalyst is that it must be pre-swollen before being used, for example, in bishpenol A synthesis.
In contrast, an object of the present invention is to provide solids which have both sulphonate or sulphonic acid groups and mercapto groups on the surface and which may be used as catalysts, for example, in condensation reactions without the risk associated with prior developments.